Tuesday, July 2, 2019

Radar Guns and Einstein's Theories

According to a NASA web site HERE, a basic police radar gun can, in theory, measure the speed of an oncoming car by sending out a single photon.  That photon hits an atom in an oncoming car as if the photon had its original energy PLUS the kinetic energy of the moving atom.  The atom cannot hold any additional energy, so it emits a new photon back toward the radar gun.  The new photon has the additional energy (and thus shorter wavelength) caused by impacting a moving object.

This conflicts with what many college text books say, since it is NOT something that the Wave Theory of light can explain if waves are viewed this way:

The image above shows repeated waves of one frequency being emitted by the radar gun in the police car and repeated individual waves of a shorter frequency being returned by the "moving car."

More importantly, police radar guns confirm Einstein's Second Postulate, which says,
“light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body.”
Yet many many college text books claim that is NOT Einstein's Second Postulate.  They falsely claim that Einstein's Second Postulate says that light travels at c independent of the emitting body and any observing body.  Radar guns clearly demonstrate every day that that is not true.  Radar guns wouldn't work if the target received photons at c.  They work because moving targets receive photons at c+v (or c-v) where v is the speed of the target.

I'm writing about this because I have a paper about Radar Guns and Einstein's Theories available at this link: http://vixra.org/pdf/1806.0027v4.pdf and I'm looking for people's comments about it.

Ed Lake


  1. Regarding the first point, of only one photon hitting an atom of the target car, consider that the new photon can be emitted in any direction (see Feynman lectures about this). There is a very very small probability that the reflected photon gets back to the gun receiver. That is the reason physicists talk of "zillions" of photons and not ONE photon. QED deals mostly on probability functions.

    The second figure shows the wave representation of the radar gun. The black lines are the wave fronts which, as shown, expand in a spherical way (this depends on the antenna radiation pattern). The lambda corresponds to the waveform wavelength, which is equal to f/c, where f is the radar transmitting frequency and c is the speed of light.
    The approaching car intercepts (due to its reflecting surface) a small part of the waveform, reflecting the wave form in a new
    wave fronts (the blue lines) which also expand in a spherical wave, with wavelength lamda', shown as shorter than lambda. It means the reflecting waveform has a HIGHER frequency, as shown in the calculator numbers.

    Regarding your cite of the second postulate, the phrase "...is independent of the state of motion of the emitting body." means that the emitting body state of motion can be either a)at rest
    or b)moving.
    Now, from the point of view of a receiver, it can also be in a state of motion given by a) or b).
    It easy to see that the pair described below are equivalent:

    Assume the emitting body is approaching the receiver. Then the following state of motion are equivalent:

    Emitting body at rest, receiver moving
    Emitting body moving, receiver at rest

  2. First, the emitted photon cannot be emitted in any direction. It is emitted from a gun, so it can only travel in the direction the gun is pointed. Besides, the one photon situation was stated to be "in theory." It is the RETURN photon that is totally unlikely to return to the gun. But, if the target is a mirror (like the polished surface of a bumper), then the odds are better.

    The paper quotes Richard Feynman's book QED as follows:

    "I want to emphasize that light comes in this form — particles. It is very important to know that light behaves like particles, especially for those of you who have gone to school, where you were probably told something about light behaving like waves. I’m telling you the way it does behave — like particles."

    So, arguments that light behaves like waves ARE NONSENSE.

    As to your last point, according to Einstein, light is emitted at c whether the emitter is moving or not. A moving observer will therefore receive the light at c+v or c-v, where v is the speed of the observer moving toward or away from the emitter.

    One intent of the paper is persuade someone to do an EXPERIMENT with one of the 3 radar guns named in the paper to see if Einstein's prediction is confirmed. If the radar gun is on a moving vehicle, the gun will show zero speed if it is pointed at a parked car regardless of how fast the gun is moving.


    1. For sure an emitted photon can have any direction. In radar guns, those direction can be any of the ones defined by the antenna radiation pattern (usually any direction in a +/- 15 spherical degrees)- So, again QED calculates the probability a photon will be emitted in any direction. It turns out that a sigle photon can be emitted and never hit a car target!!!.

      Regarding the Feynman quote, you should read the rest of that book (which is not very technical to begin with) and see the video at
      Note how he talks about waves mechanics!!!

      Regarding the c+v or c-v stuff I remind you that those are
      CLOSING SPEEDS, which are measured from a third frame of reference.

      Let me put an example: two cars A and B are approaching eachother in a highway. Car A is moving at 60 mph to the East, while car B is moving at 60 mph to the west. It turns out that the closing speed is 120 mph which obviously is not measured from the ground!!